The present invention relates to a method of intubating a patient, particularly a patient to be anesthetized, and to an introducer for use with such method.
In the course of surgery or other medical procedures, it is commonly necessary to anesthetize the patient, and this frequently requires that the patient be ventilated during the procedure, such ventilation is achieved by way of an endotracheal tube. Endotracheal intubation, placement of a breathing tube into the trachea, is commonly performed after induction of general anesthesia to maintain a patent airway and prevent aspiration of oral secretions or stomach contents into a patient's lungs. Usually, the tube is passed through the mouth and into the trachea under direct vision of the larynx at the tracheal opening. A specialized flashlight or laryngoscope is used to hold the tongue and airway structures out of the way, including the epiglottis, a structure above the larynx that functions to prevent entrance of food and liquid into the lungs as we swallow. Individual variation in patients' anatomy occasionally makes it difficult to see past the epiglottis even with proper use of the laryngoscope.
If a difficult intubation is encountered, one of several accepted methods may be used to facilitate correct tube placement despite inability to directly view the opening to the trachea. One of these methods involves using an introducer as a guide. The most common introducers are long, non-hollow and flexible, yet malleable enough to hold a curved shape in one end. With the introducer threaded through an endotracheal tube, the curved end of the introducer is used to probe gently behind the epiglottis until the trachea is entered by feel rather than under direct vision. The endotracheal tube is then guided over the introducer and into the trachea. The introducer is then removed and the position of the endotracheal tube is confirmed by the usual methods.
A common risk associated with introducer assisted difficult intubations is inadvertent esophageal placement of the endotracheal tube. Esophageal intubation itself, recognized and quickly corrected, is not likely to harm the patient. However, there exists the possibility of gastric distention, vomiting, and aspiration after attempts to ventilate through a tube placed in the esophagus. Also there may be a delay in providing adequate ventilation to the lungs. If one could reliably confirm that the introducer is in the trachea rather than the esophagus before passing the endotracheal tube over the introducer, these risks could be avoided.
One way to confirm tracheal rather than esophageal placement of an introducer, is sample gas through a hollow lumen from holes drilled in the side of the introducer near its curved tip. With rare exceptions carbon dioxide is present in exhaled gasses sampled from the trachea but not in the esophagus. This distinction is commonly used to confirm correct tracheal placement after an endotracheal tube has been placed, by whatever means, by measuring the amount of carbon dioxide in gas sampled through the tube. It thus became possible to distinguish tracheal from esophageal placement of an introducer by measuring carbon dioxide sampled through the hollow lumen of the introducer. However, reliance of this method in clinical practice is questionable because what was sampled was tracheal gas from introducers that were passed into the trachea through a previously placed endotracheal tube. In clinical practice, the position of the introducer would need to be confirmed before the endotracheal tube would be placed.
Hollow lumen tubes which are similar in size and shape to conventional introducers are available and are used for other purposes. One such tube is marketed as Jet Stylet or Endotracheal Tube Changer. This device is used when removing or changing a previously placed endotracheal tube when there is concern about the possibility of a difficult re-intubation. The Jet Stylet is placed into the Trachea through the lumen of a previously placed endotracheal tube. The tube is then withdrawn over the stylet and removed while the stylet remains in the trachea. If re-intubation is required, a new tube can then be placed over the stylet and into the trachea (using the stylet exactly as one would use an introducer that is already correctly placed in the trachea). A significant benefit of a Jet Stylet is the ability to give oxygen to the patients lungs through the hollow lumen if necessary. The term Jet Stylet is used because high pressure oxygenation through a small lumen catheter is known as jet ventilation and is one alternative that can be used when normal endotracheal intubation cannot be accomplished.
It will be seen from the above that even skilled anesthesiologists will at times be uncertain as to whether the introducer has in fact been placed into the trachea rather than the esophagus, and it is, therefore, the object of the present invention to provide a way of making certain that first the introducer, and ultimately the endotracheal tube, is in fact properly positioned in the patient's trachea rather than in his or her esophagus.